author | Szabolcs Nagy <nsz@port70.net> | 2013年05月18日 12:34:00 +0000 |
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committer | Szabolcs Nagy <nsz@port70.net> | 2013年05月18日 12:34:00 +0000 |
commit | 1d5ba3bb5a3f55e10db05219638cfcd967d65417 (patch) | |
tree | 4cf78f97777619d73e91ba3c1431aadc434b3fe8 /src/math/tanl.c | |
parent | 22730d65608db06500cc6e0be4aaec03238f996b (diff) | |
download | musl-1d5ba3bb5a3f55e10db05219638cfcd967d65417.tar.gz |
-rw-r--r-- | src/math/tanl.c | 37 |
diff --git a/src/math/tanl.c b/src/math/tanl.c index 0194eaf7..3b51e011 100644 --- a/src/math/tanl.c +++ b/src/math/tanl.c @@ -41,42 +41,27 @@ long double tanl(long double x) long double tanl(long double x) { union IEEEl2bits z; - int e0, s; long double y[2]; - long double hi, lo; + unsigned n; z.e = x; - s = z.bits.sign; z.bits.sign = 0; - /* If x = +-0 or x is subnormal, then tan(x) = x. */ - if (z.bits.exp == 0) - return x; - /* If x = NaN or Inf, then tan(x) = NaN. */ - if (z.bits.exp == 32767) + if (z.bits.exp == 0x7fff) return (x - x) / (x - x); - /* Optimize the case where x is already within range. */ + /* |x| < (double)pi/4 */ if (z.e < M_PI_4) { - hi = __tanl(z.e, 0, 0); - return s ? -hi : hi; + /* x = +-0 or x is subnormal */ + if (z.bits.exp == 0) + /* inexact and underflow if x!=0 */ + return x + x*0x1p-120f; + /* can raise spurious underflow */ + return __tanl(x, 0, 0); } - e0 = __rem_pio2l(x, y); - hi = y[0]; - lo = y[1]; - - switch (e0 & 3) { - case 0: - case 2: - hi = __tanl(hi, lo, 0); - break; - case 1: - case 3: - hi = __tanl(hi, lo, 1); - break; - } - return hi; + n = __rem_pio2l(x, y); + return __tanl(y[0], y[1], n&1); } #endif |